Fertiliser additive Kicka can reduce nitrogen use by up to 20 per cent, according to a seven year study.

The UK tested additive, when applied close to the planted seed, could enable potato farmers working medium to low fertility soils to slash nitrogen rates by 100kg/ha without major impact on yield.

Peter Jones, potato specialist at Masstock, said: ""It could be significant for farmers complying with NVZ and RB209 rulings and could bring environmental benefits from a reduction in nitrogen use. It will improve potato crop gross margins, too.

"With ammonium nitrate at £190/tonne, Estima at £100/tonne and Kicka at £65/hectare, the margin over input costs was a creditable £990 - a definite plus.

"In Cheshire, Kicka applied with the lowest nitrogen level resulted in 53 per cent more marketable yield from 37 per cent more tubers. The following year, although the response was less dramatic, the plots with 150 kg/ha nitrogen and Kicka gave over 23 per cent more marketable yield than those without. This treatment had 11% more tuber numbers."